The seats in a motor vehicle, in particular the driver's seat, are typically provided with some device for adjusting the position thereof so as to ensure that the seat is at the desired height for the driver's visibility and at the desired spacing from the steering wheel and pedals. Many seats are also provided with other comfort settings that can also be adjusted. The adjusting devices can be either manual or powered by one or more motorized mechanisms. Motor vehicle seats are commonly formed with a frame, onto which the cushions and upholstery etc. are provided. Height adjustment devices are typically mounted to the frame so as to allow the entire seat assembly to be raised or lowered as needed.
Various devices and mechanisms are known in the art for manually adjusting the height of seats in vehicles. Generally, such devices comprise a manual actuator, such as a spring activated lever, that is connected to a seat height adjustment mechanism provided in a seat assembly. Such actuators are generally provided with a clamping or braking mechanism, for locking the height adjustment mechanism so as to position the seat at a desired height. The occupant of the seat engages the actuator to release the clamp or brake, adjusts the seat to a desired height, and releases the actuator to clamp the seat in the desired position. It is also common for such manual actuating devices to include a clutch mechanism to facilitate the height adjustment process by preventing the weight of the passenger from acting against the actuator. Examples of known manual seat adjustment devices and actuators are provided in the following documents: U.S. Pat. No. 4,648,575 (Kawade); U.S. Pat. No. 6,212,965 (Hochmuth); U.S. Pat. No. 7,182,196 (Weber); and U.S. Pat. No. 2007-0227854 (Cabrit).
Some of the known manual seat height actuators or devices utilize a friction-based mechanism for achieving the required clamping forces. In such known devices, a number of balls, i.e. ball bearings (U.S. Pat. No. 6,212,965) or rollers (U,S. Pat. No. 2007-0227854) are forced by springs into a space or channel bounded by two members. Once the balls are frictionally engaged into such channel, relative movement between the two members is prevented.
The mechanisms used in many known devices for raising and lowering of seats tend to be clumsy, cumbersome and difficult to operate. The known devices are also generally expensive (due, for example, to the use of machined components) and are either large and/or heavy, which are undesirable characteristics when manufacturing vehicles having cost constraints, and space and weight restrictions.
The present invention seeks to alleviate one or more of the drawbacks of the known seat height actuating devices.